Preheat oven to 220°C (200°C fan). Line a large baking tray with parchment paper and brush lightly with olive oil.

Grate the potatoes using a box grater or food processor. Place in a clean kitchen towel and squeeze out as much moisture as possible.

Transfer the dried potatoes to a bowl and toss with 2 tablespoons olive oil, salt, pepper, and garlic powder until evenly coated.

Spread the potato mixture evenly onto the prepared baking tray, pressing firmly to form a thin, even crust about 30cm in diameter. Bake for 20 minutes until edges are golden and crispy.

Meanwhile, heat remaining olive oil in a large frying pan over medium-high heat. Add sliced mushrooms and cook for 5-6 minutes until golden brown and tender.

Add minced garlic to the mushrooms and cook for 1 minute until fragrant. Remove from heat and stir in fresh thyme and rosemary. Season with salt and pepper.

Remove the potato crust from oven. Spread crème fraîche evenly over the crust, leaving a small border. Sprinkle with half the mozzarella.

Arrange the sautéed mushrooms over the cheese, then top with remaining mozzarella and Parmesan.

Return to oven and bake for 12-15 minutes until cheese is melted and bubbly with golden spots.

Remove from oven and let rest for 2 minutes. Top with sliced spring onions and fresh rocket leaves. Slice and serve immediately.